Knife sharpener



March 19, 1957 BRANNAN 2,785,517

KNIFE SHARPENER Filed Jan. 27, 1954 INVENTOR. I A 66 K742777477.

iinited States Patent KNIFE SHARPENER Lee Brannan, Detroit, Mich.

Application January 27, 1954, Serial No. 406,409

Ciaims. (Cl. 51-213) This invention relates to a wet grinding or oil grinding knife or tool sharpener of the type wherein the operator strops the knife or tool back and forth across an abrasive surface. More specifically, the invention relates to a knife or tool sharpener wherein the edge to be ground is drawn across an abrasive surface free to move in the same direction as the relative motion between the two.

For use in the home, kitchen or workshop, conventional sharpening tools or devices are unsatisfactory for the homemaker or the amateur or unskilled workman. The use of the conventional sharpening steel, file or flat oil-stone requires considerable skill to obtain a good edge. Moreover, the grinding action of these sharpening devices is slow and not well-adapted to removing any considerable weight of metal. Consequently, it is necessary to periodically have the tools reground by a professional, reserving the conventional sharpening devices for minor dressing operations only.

It is an object, therefore, of this invention to provide a more satisfactory hand-grinding device for knives, tools and the like which does not require a steady hand or great skill in the operator.

Another object is to provide an inexpensive sharpener making possible the use of wet-grinding for these purposes.

Still other objects, features and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

Figure l is a perspective view of an embodiment of the sharpening device for this invention;

FigureZ is a section taken along the line 2-2 of Figure 1;

Figure 3 is a partial sectional view taken along the line 3-3 of Figure 1;

Figure 4 is a partial sectional view represented as if taken along the line 3-3 of Figure 1, showing a second embodiment of a bearing structure for use in the device of Figures 1 to 3; and,

Figure 5 is a partial sectional view showing a modified form of bearing structure for the device of Figure 1.

In the drawings, the same reference numerals are applied to the same parts throughout the several views.

Referring to Figure 1, there is provided a rectangular container comprising a central body section 20, a lefthand end section 21 and a right-hand end section 22. The central body section 20 is hollowed out to form a longitudinally disposed semi-cylindrical oil trough 23 having at the bottom a longitudinal groove 24 running the length thereof. The oil trough 23, of course, need not be semi-cylindrical but is preferably of that shape in order to insure collection of debris in the trough 24. The trough 23 serves as a receptacle for the oil, water or other cutting agent while the groove 24 serves to catch the metal filings, abrasive residues and other debris produced during use. The end sections 21, 22 are provided with hearing housings 25, 26, located so as to be centered in the plane of the upper body surface, and fitted to receive bearings. One of these housings, for example, the hous- 2,785,517 Patented Mar. .19, 195.7

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7 ing 25 in the right-hand end section 22 in Figures 1 and 3, is adapted to receive a full ball bearing race 27. The left-hand housing 26 is then of the snap-on type adapted to be fitted with a half-race or split race 28 of the ball bearing type (Fig. 3), or roller bearing; type (Fig. 4). Other types of low friction bearing means may be utilized as well as the ball and roller types illustrated.

Suspended in the trough 20 and bearings 27, 28, there is provided an elongated cylindrical abrasive stone 30, which has a length greater than its diameter and preferably having a length at least three times its diameter. Most preferably, the length of the stone is at least five and up to ten times its diameter. The ends 31, 31 of the stone 30 are provided with identical brass or other metal stub shafts 32, 32 which are journaled in the bearing races 27, 28 so that the stone will freely rotate when a knife or other tool is passed transversely over its upper exposed surface. Since the left hand bearing 28 is of the half-race or split-race types, the stone 30 is easily removable for replacement, redressing or for cleaning of the trough 23.

in Figure 4 is illustrated a roller bearing race 40 which may be utilized in place of the full ball bearing race 27 on the right-hand end of the stone. It will be apparent that half races may be utilized on each end of the stone, if desired.

In use the trough 23 is filled partially full of oil, water or other cutting agent which will suspend metal and abrasive particles loosened in the sharpening operation. A knife, for example, is stropped on the stone with much the same action as is used by a chef in stropping a carving knife on a sharpening steel. That is, the knife is passedlengthwise of the stone with a concurrent rotary motion to the wrist. The slight rotary motion of the wrist is sufficient to exert a rotary component of force on the stone to cause the latter to rotate freely in the bearings. In this way, the once used portion of the stone is advanced and a new oil-wetted surface always presented to the metal. Not only does this result in a continuous cleaning of the stone, but prevents the generation of flat spots on the cylindrical outer surface of the stone. Thus, the stone wears evenly and there always will be presented to the edge to be ground a surface of maximum curvature. In the sharpener of this invention the small diameter of the stone relative to its length is believed to greatly speed the cutting action. Thus, a relatively small number of passes over the stone will quickly and efficiently whet a relatively thick cutting edge.

For even greater cutting action, the illustrative knife or tool is passed across the stone at a sharply oblique angle, meanwhile firmly grasping both ends of the blade so as to steady it and exert the desired pressure. In most cases, the knife need only be grasped by the handle meanwhile pressing lightly on the side of the blade with the fingertips of the other hand. An unskilled operator need only make one or two experimental passes to determine the angle between the blade and stone necessary to expose the correct area of the thick portion of the dull blade to the stone. Even the hardest of cutlery steel is rapidly ground away because of the relatively high pressures generated by the slightest pressure between the metal and the small radius of curvature of the stone. Because of the freedom of the stone to rotate, however, it is possible to obtain extremely light pressures between the blade and the stone and to finish dress the blade to a fine edge.

The device described herein is inexpensively made of common impervious materials. For example, both the central body portion and the end sections may be made of a good grade of hard wood. The central body portion and end sections can also be pressed out of single pieces of inexpensive sheet steel of moderate thickness. Assembly can be made in either case by suitable screws, bolts, or other fasteners not shown in these drawings. For heavy duty use :in restaurant or hotel kitchens, or in commercial workshops, the body and end sections .can be cast in one integral piece .from cast iron, aluminum or carved vfrom a block of any other suitable material impervious to oil, water and other cutting agents.

.For best results with the device of this invention, the stone is preferably long compared to its diameter. It has :been found that when the length is at least three times the diameter, the fastest cutting speed and quality of edge finish is obtained. More preferred is a length at leastfive times the diameter. In general, stones below four inches in diameter .cut fasterand rotate more easily than stones of greater diameter .and mass. The stone, however, shouldhave a mass such that it does notrotate too easily. Solid natural or cemented stones of dimensions described Work efficiently when hung in ball or roller bearings. The maximum length of stone is not critical except that longer stones become more fragile and have so great a mass as not to be rotatable with the ease required for satisfactory cleaning and even wear, especially when small tools are sharpened. A practical maximum length would be 18 to 24 inches.

The stone itself may be a solid cylinder of any natural stone or abrasive or an artificial cemented abrasive of any of the common types commercially available. Particularly satisfactory, because of their uniformity and great strength, are any of the resin-bonded corundum, silicon carbide, and similar abrasives.

While it will be apparent that thepreferred embodiments of the invention herein disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation .and change Without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

l. A sharpening device for knives and other tools comprising a receptacle of impervious material having a trough therein .having a length at least three times its diameter, bearings and their housings located in opposite ends of said receptacle adjacent the ends of said trough, and a solid cylindrical abrasive stone having axially disposed means extending a short distance into said stone at each end thereof, said stone being substantially coextensive in length with said trough and suspended in said trough in said bearings and housings so as to be freely rotatable therein.

.2. A knife sharpener comprising a horizontally disposed central body section of impervious material, an upstanding end section attached to each end of said body section, semi-cylindrical trough-like depression in the upper surface of said body section, a ball-bearing located in each of said end sections, and an elongated solid cylindrical abrasive stone having axially disposed shaft means extending a short distance into said stone at each end thereof, said stone having a length at least five times its diameter and being suspended in said bearings so as to be freely rotatable in said trough-like depression.

3. A knife sharpener comprising a horizontally disposed central body section of impervious material, an upstanding end section attached to each end of said body section, semi-cylindrical trough-like depression in the upper surface of said body section, a roller bearing located in each of said end sections, and an elongated solid cylindrical abrasive stone having axially disposed shaft means extending a short distance into said stone at each end thereof, said stone having a length at least five times its length and being suspended in said bearings so as to be fully rotatable in said trough-like depression.

4. A knife sharpener comprising a horizontally disposed central body section of impervious material, an upstanding end section attached to each end of said body section, semi-cylindrical trough-like depression in the upper surface of said body section, a longitudinal groove running the length of said trough-like depression and located at the bottom thereof, a full ball bearing race located in one of said end sections and a half ball bearing race located in the other of said end sections, and an elongated solid cylindrical abrasive stone having a length at least five times its diameter suspended in said bearings so as to be easily removable therefrom and freely rotatable in said trough-like depression.

5. A sharpening device consisting of the combination of an elongated abrasive stone and supporting means therefor, said stone being solid and having axially disposed means extending a short distance into said stone at each end thereof, said stone having a length at least three times its diameter, said supporting means having bearing means located in opposite ends thereof and a semi-cylindrical trough in the upper surface of said supporting means having a diameter slightly greater than the diameter of said stone, said stone being mounted in said bearing means so as to be freely rotatable in said trough.

References Cited in the file of this patent UNITED STATES PATENTS 130,660 Quipp Aug. 20, 1872 366,897 Stiles July 19, 1887 367,331 Barnes July 26, 1887 516,353 King Mar. 13, 1894 1,617,536 Miles Feb. 16, 1927 2,496,139 Vass Jan. 31, 1950' 

